Dynamo-electric machine.



No. 627,937. Patented June 27, I899.

L. o. LIEBER.

DYNAMU ELECTRIC MACHINE.

(Application. 512a Feb. 2, 1899.

(No Model.) 2 Sheets$heet l.

No. 627,937. v Patented lune 27, I899. L. 0. LIEBER.

DYNAMO ELECTRIC MACHINE.

(Applicntion fllod Feb. 2, 1899.)

2 Sheets-Sheet 2.

("0 Model.)

We Momma PETERS co.. PHOTO-LITHOY, wwsmumou, n. c.

UNITED STATES PATENT OFFICE.

LOUIS OTTO LIEBER, OF LOS ANGELES, CALIFORNIA.

DYNAMO-EL'ECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 627,937, dated J time 27, 1899.

Application filed February 2, 1899. Serial No. 704,262. (No model.) I

To all whom; it may concern:

Be it known that I, LOUIS OTTO LIEBER, residing at Los Angeles, in the county of Los Angeles and State of California, have invented a new and useful Improvement in Dynamo- Electric Machines, of which the following is a specification.

My invention relates to electrical generators or dynamos in which the number of commutator-bars is indivisible by the number of poles; and the object of my invention is to prevent the sparking and heating which are common to electrical machines of this kind as heretofore constructed.

My invention also applies to any dynamoelectric machine, in that'in my machine the contact-face ofeach of the brushes is ofa width less than that of all of the commutator-bars of one polarity which connect with one series or group of the winding and greater than that of all of said bars less one, and the relation of the brushes to the bars with which they respectively contact is uniform throughout the armature. That is to say, at any instant any brush has the same position relative to the bars with which it contacts as any other brush in contact with the commutator of the armature, and the transition fromthe bars of one polarity is made without any break in the series or group of the winding of the same polarity of any brush.

The accompanying drawings illustrate my invention.

Fignre l is a fragmental view of a dynamo embodying my invention in one form, showing an end elevation of the commutator with brushes in place to illustrate the principle of this invention and the mode in which it is carried out. Fig. 2 is a fragmental detail showing a brush of one polarity in contact with three bars of the commutator. Fig. 3 shows a brush of the opposite polarity in contact with three other bars. Fig. 4 is a view of a fragment of the commutator and the winding, showing, diagrammatically, the series or groups of the winding of a triple parallelwound armature.

A indicates a commutator having eight hundred bars a. V

The numerals from 1 to 12 indicate the poles or brushes, which are twelve in number in the instance illustrated. In the drawings a triple winding may be understood. The contact-face of each of the brushes is of less width than all of the com mutator-bars of one polarity which connect with one series or group in the winding, said brushes being arranged in their relation to the bars in overlapping groups, which in the drawings are respectively numbered group 1, group 2, group 3, and group t, lines being drawn in the view from center to center of the outside brushes of each group. By overlapping groups I mean to say that the lastbrush of the one group is the same as the first brush of the succeeding group, and with relation to all of the groups the first brush of group 1 is the last brush of group 4. The number of said groups of brushes in any machine is determined, being equal to the diiference between the whole number of commutator-bars and the next higher multiple of the number of poles. For example, in the comm utator shown, having eight hundred bars and twelve poles, the next higher multiple of the number of poles is eight hundred and four, and therefore the brushes are arranged in four overlapping groups. The respective spaces between the centers of the outside poles of the several groups are uniform, and each is equal to the space occupied by an even number of bars, and the space from center to center of any two poles is a multiple of the space between the centers of two succeeding bars. In order to make this arrangement, it becomes necessary to place the brushes at varying distances apartthat is to say, in the generator shown any group includes two hundred bars; but the space from center of pole 1 to center of pole 2 may be sixty-seven bars, the space from center of pole 2 to center of pole 3 may be sixty-seven bars, and from center of pole 3 to center of pole t must then be sixty-six bars.

By reference to Figs. 2 and 3 it will be seen that the brushes of opposite polarity stand in the same position, respectively, with relation to the bars with which they respectively contact, and by reason of the peculiar arrangement which I have set forth above this correspondence is never disturbed--that is to say, the positive brush is always in the same relation to the bars with which it contacts as the brush of an opposite polarity. This is not true in armatures of dynamo-electric machines as ordinarily constructed. It will also be seen from these views that the brush is narrower than three bars and is wider than two bars and will therefore contact with a fourth bar at the moment of transition from bar to bar.

In Fig. 4 the bracket Z embraces all of the commutator-bars of one polarity which connect with one series or group B of the winding b. The brush 1 is shown in contact with the four bars which connect with a group B of the winding 1). The brush3 is shown in contact with the four bars which connect with another group B of the winding 1).

In any machine in which the brushes are placed in the manner above stated while under load all sparking is done away with,

local currents are reduced, the heating is decreased, and it is not necessary to provide for any change of position of the brushes on any variable load. On shutting down a machinehaving said adjustment the regulating devices controlling the fields must he allowed such position as to allow the current to circulate on fields while shutting down after the load is thrown off until the machine is at a standstill; otherwise there will be a burning or sparking of brushes after the load is thrown oif.

The machine which I have taken for an instance to illustrate my invention is an eighthundred-kilowatt machine.

Now, having described my invention, what Iclaim as new, and desire to secure by Letters Patent, is

1. In an electrical machine in which the number of commutator-bars is indivisible by the number of poles, the combination with the commutator, of brushes, the contact-face of each of which is or" a width less than that of all of the commutator-bars of one polarity which connect with one series or group in the winding, and greater than that of all of said bars less one; said brushes being arranged in their relation to the bars in overlapping groups; that is to say the last brush of one group being the first brush of the succeeding group; said groups of brushes being equal in number to the difference between the whole number of commutator-bars and the next higher multiple of the number of poles, the space between the centers of the outside poles of each of the several groups being uniform and each equal to the space occupied by an even number of bars, and the space from center to center of any two poles being a multiple of the space between the centers of two successive bars.

2. In an electrical machine, the combina tion with the commutator, of brushes the contact-face of each of which is of a width less than that of all of the commutator-bars of one polarity which connect with one series or group of the winding, and greater than that of all of said bars less one; the relation of the brushes to the bars with which they respectively contact being uniform throughout the winding.

LOUIS OTTO LIEBER. \Vit-n esses:

JAMES R. TOWNSEND, F. M. TOWNSEND. 

